讀線性代數遇到的東西

不一樣！後者： V∖W = {v ∈ V : v ∉ W}"the (set) difference of V and W" 差集前者： V/W = {{v+w : w ∈ W}, v ∈ V}"the quotient space of V modulo W"quotient space 商空間Friedberg, Insel, Spence. Linear Algebra, Third Edition 其定義及相關結果出現在該書的習題裡引索裡找 "Quotient space" 就有了
定義出現在第 22-23 頁Let W be a subspace of a vector space V over a field F. For any v ∈ V, denote by v+W the set {v+w: w ∈ W}, called the coset of W containing v.The operations + and ● on S = {v+W : v ∈ V} defined by by(v1+W) + (v2+W) = (v1+v2)+W  (v1, v2 ∈ W)a ● (v+W) = (av+W)  (v ∈ V, a ∈ F)turn S into a vector space, the quotient space of V modulo W, denoted by V/W.